The invention relates to a perimeter for measuring a visual field (perimetry), and especially relates to a perimeter having a visibility corrector, such as a lens holder, to which a correction lens is attachable.
A perimeter with a mechanism for locating visibility corrector, such as a lens for correcting the visibility of an eye to be examined, has been known, as disclosed in Patent related document 1 mentioned hereinafter.
Perimetry takes a longer time, and a fixation state of an eye to be examined may be shifted during the perimetry. In such a state, it is not possible to obtain a correct measurement result. For this reason, a fixation state monitor for detecting whether the fixation state of the eye to be examined is stable has been proposed as disclosed in Patent related documents 1 and 2 mentioned hereinafter. Furthermore, Patent related documents 4 discloses such an art that credibility of the measurement value is judged and such a judgment is set as a standard at a time of reexamination.